A stent-graft (a stent with a graft layer lining or covering it) is typically used to provide a prosthetic intraluminal wall, e.g., in the case of a stenosis or aneurysm, to provide an unobstructed conduit for blood in the area of the stenosis or aneurysm. A stent-graft may be endoluminally deployed in a body lumen, a blood vessel for example, at the site of a stenosis or aneurysm by so-called “minimally invasive techniques” in which the stent-graft is compressed radially inwards and is delivered by a catheter to the site where it is required, through the patient's skin, or by a “cut down” technique at a location where the blood vessel concerned is accessible. When the stent-graft is positioned at the correct location, the stent-graft is caused or allowed to re-expand to a predetermined diameter in the vessel.
A one branch design stent-graft is typically utilized at a native vessel bifurcation to direct fluid into only one of the branches of the bifurcation. For example, an aorto-uni-iliac stent-graft provides an unobstructed conduit for blood to flow from the aorta through only one of the two iliacs. As used in the aorta, blood flows through the single branch stent-graft to the bifurcated vessel branch of the native bifurcation that contains the stent-graft, while blood is prevented from flowing to the other bifurcated branch of the native bifurcation.
Typical single branch design stent-grafts have a tendency to work their way distally from the originally deployed position. It will be appreciated by a person skilled in the art that it is desirable to prevent stents from migrating out of position. In particular, where the site of desired application of the stent or prosthesis is a native vessel bifurcation, the distal migration associated with the use of the prior art prostheses constitutes a significant disadvantage.